print("计科1914-02-陈鸿宇")
score = float(input("请输入学生的成绩:"))
if score >= 100 or score < 0:
    print("成绩有误!")
elif 90 <= score <= 100:
    print("A")
elif score >= 80:
    print("B")
elif score >= 70:
    print("C")
elif score >= 60:
    print("D")
else:
    print("E")
